This application focuses on the mechanisms of EGF receptor signaling. The investigator has recently identified a new protein ZPR1, which binds to the tyrosine kinase region of the EGF receptor. EGF binding to its receptor decreases the binding of ZPR1 thus releasing this protein from the EGF receptor following receptor activation. The investigator wishes to determine the functional significance and mechanisms of ZPR1 binding to the EGF receptor signaling pathway. Three aims are proposed. In the first aim, the investigator will determine the role of ZPR1 in EGF receptor signal transduction. In the second aim, the investigator will attempt to identify target molecules that interact with ZPR1. In the third specific aim, the investigator will determine ZPR1 function using genetic analysis in yeast.